Tilt switch

ABSTRACT

A tilt-sensitive electrical mercury switch wherein the mercury chamber comprises upper and lower spaced walls of essentially conical shape having the cone apexes oriented downward and the two-cone bases joined at their peripheries to form a fluid-tight chamber; various embodiments for restricting splashing of the mercury are provided.

United States Patent Wade M. Johnson;

Harry L. Mussett, Ponca City, Okla. 830,360

June 4, 1969 Jan. 12, 197 l Contnental Oil Company Ponca City, Okla.

a corporation of Delaware [72] Inventors [21 App] No, [22 Filed [45]Patented [73] Assignee [54] TILT SWITCH 1,618,608 2/1927 Smith ZOO/61.471,858,191 5/1932 ZOO/61.47 2,130,500 9/1938 ZOO/61.47 2,056,877 10/1936ZOO/61.47 2,161,411 6/1939 Erich 200/61.47 2,192,262 3/1940 GriesedieckZOO/152.7 2,522,721 9/1950 Matterrl 200/152 3,036,296 5/1962 Conte200/61.47X 3,163,726 12/1964 Kalish et a1. 200/61.47X

Primary Examiner-Robert K. Schaefer Assistant Examiner-M. GinsburgAtt0rneys.loseph C. Kotarski, Henry H. Huth, Jerry B. Peterson, WilliamA. Mikesell, Jr. and Carroll Palmer ABSTRACT: A tilt-sensitiveelectrical mercury switch wherein the mercury chamber comprises upperand lower spaced walls of essentially conical shape having the coneapexes oriented downward and the two-cone bases joined at theirperipheries to form a fluid-tight chamber; various embodiments forrestricting splashing of the mercury are provided.

ATENTED JAN 1 21am FIG.

FIG. 4

FIG. 3

INVENTORS. WADE M. JOHNSON HARRY L. MUSSETT' BY I "L-22 3mm C 724% ad!g1 ATTORNEY TILT SWITCH This invention relates to a novel tilt-sensitiveelectrical mercury switch configuration.

Tilt-sensitive switches comprising a chamber containing a pool ofmercury which opens or closes an electrical circuit between a pair ofelecrodes upon appropriate tilting have long been known. One problemexisting with such switches has been their sensitivity to vibration,i.e. when rigidly mounted on a motor vehicle or other equipment subjectto vibration, the mercury can splash and thus open or close a circuiterroneously when the switch has not been subjected to the necessarytilting.

It is accordingly an object of this invention to provide a mercuryswitch wherein the tendency of the mercury pool to splash when itschamber is subjected to vibration or jogging is diminished. Anotherobject of the invention is to provide a mercury switch sensitive toactuation by tilting in any direction.

Other objects and the several advantages of this invention will becomeapparent upon study of this disclosure, the appended claims, and thedrawing, in which:

FIGS. 14 represent vertical cross-sectional views of various embodimentsof the invention.

Referring now to the drawing, and to FIG. 1 in particular, a chamberindicated generally as contains a pool of mercury 11 and two or moreelectrodes 12. According to the present invention, chamber 10 comprisesan'upper wall 13 and a lower wall 14, both generally conical inconfiguration. Walls 13 and 14 are spaced apart sufficient to permitfree flow of mercury therebetween, i.e. to avoid surface tensioneffects. The downwardly oriented apex of lower wall 14 is preferablyrounded, as shown, so as not to present crevices or sharp corners whichwould by surface tension impede the free movement of mercury 11. In theembodiment of this FlG., the apex of upper wall 13 is convex upwardly ata distance from lower wall 14 as to conform to or just clear the uppersurface of mercury 11. Upper wall 13 and lower wall 14 are joinedtogether at the peripheries of their bases, i.e. at their upper ends, soas to make chamber 10 fluid-tight, preferably so as to present a smoothor rounded inner surface as shown. Electrodes 12 are suitably sealedwhere they pass through the walls of chamber 10, as at 15. In thisembodiment, one electrode 12 enters the chamber through upper wall 13,and another through lower wall 14. When a normally closed switch isdesired, the inner ends of both electrodes 12 terminate within the bodyof liquid mercury 11, preferably near the center thereof, with themercury in its normal position between the apexes of the walls.

Referring now to FIG. 2, this embodiment differs from that of FIG. 1 inthat the resistance to mercury-splashing is provided by the shape oflower wall 14, rather than by the convex apex of upper wall 13. Lowerwall 14 in the present embodiment is provided with a necked-in portion16, which is so spaced from upper wall 13 as to resist splashing of alarge portion of the mercury therebetween but to permit free flow upontipping of chamber 10 about its vertical axis. Necked-in portion 16 alsoprovides a quick, clean break" of contact between the electrodes upontipping when the mercury has cleared the hump provided thereby. In thisembodiment, both electrodes 12 enter chamber 10 through lower wall 14.

In the embodiment of FIG. 3, both upper wall 13 and lower wall 14 are ofgenerally conical with smoothed apex portions, and resistance tosplashing of the mercury is provided by a also illustrates an embodimentof electrodes l2 wherein one electrode 12 terminates within chamber 10in theform of a ring surrounding and spaced from the inner end of theother electrode 12. This FIG. further illustrates and electrode 12',here a circular ring, spaced some distance above the normal uppersurface of mercury 11 and suitably connected to an external circuit by aconductor and seal means not shown. Electrode 12' is used in conjunctionwith an electrode 12 to provide a normally open switch action, andchamber 10 must obviously contain sufficient mercury to provide acircuit between these electrodes when in a tipped position.

The inclination of wall 14 with respect to the vertical axis of theswitch obviously controls the amount of tilt necessary to actuate theswitch and, because of the symmetry about its vertical axis, the switchis actuable by tilting in any direction from the vertical.

Chamber 10 can be fabricated in one or more pieces, and can be made ofinsulating material such as glass or any number of plastics, the primaryrequirement being that mercury does not amalgamate with the chamberwall. The electrodes are made of suitable electrically conductivematerial which preferably does not amalgamate. Although any electricallyconductive liquid can be used in the chamber, mercury is far preferredbecause of its high specific gravity and resistance to electrolysis.

Various features shown in the FIGS. can obviously be interchanged andcombined with those of other FIGS. For example, restriction screen 17 ofFIG. 3 can be used in conjunction with the electrodes configuration ofFIG. 2, etc.

Although this invention has been described with respect to particularembodiments thereof, it is not to be so limited, as changes andmodifications may be made therein which are within the spirit and scopeof the invention as defined by the appended claims.

We claim:

1. Tilt-actuable electrical switch means comprising a chamber meansdefined by spaced inner and outer wall means of generally conicalconfiguration, said wall means being joined at their peripheries,electrically conductive liquid within said chamber means, electrodemeans terminating within said chamber means, and motion restrictionmeans comprising a convexity of said inner wall means at the apexthereof toward the base thereof, the space between said motionrestriction means and said outer wall means being substantially filledby said electrically conductive liquid.

2. The device of claim 1 wherein said electrode means comprises coaxialconductor means having insulating means in an annular space thereof.

3. The device of claim 1 wherein said electrode means comprises a firstsubstantially linear conductor means and a second conductor meansterminating in a ring adjacent to and spaced from the end of said firstconductor means.

1. Tilt-actuable electrical switch means comprising a chamber meansdefined by spaced inner and outer wall means of generally conicalconfiguration, said wall means being joined at their peripheries,electrically conductive liquid within said chamber means, electrodemeans terminating within said chamber means, and motion restrictionmeans comprising a convexity of said inner wall means at the apexthereof toward the base thereof, the space between said motionrestriction means and said outer wall means being substantially filledby said electrically conductive liquid.
 2. The device of claim 1 whereinsaid electrode means comprises coaxial conductor means having insulatingmEans in an annular space thereof.
 3. The device of claim 1 wherein saidelectrode means comprises a first substantially linear conductor meansand a second conductor means terminating in a ring adjacent to andspaced from the end of said first conductor means.